I wouldn't say forced, he didn't threaten her or anything but she was intimidated, and she still took the tiara, I would understand her if she was groomed into doing it or she was threatened but a knight got intimidated cuz he captain looked scary, is a bit too much of a stretch it was mostly the captains fault, and I sympathize with her fear, but as a knight she buckled way too quickly put the tiara on her head, the gesture and her facial expression shows she feels bad for complying and is scared of him what she has become but the action if putting in the tiara and bit just holding shows how her greed was very active in her decision and how she partly genuinely accepted her payment.
She was already to obsessed with money so it was particularly easy to make it worse, if she had been less greedy maybe things would have turned out different (not victim blaming, she k ows herself she has done unforgivable things for the sake of money, but she also knows that she is not the sole perpatrator, she was just a tool, she gave him the opportunity to mold into whatever he wanted) it's like a bully making a deal with the devil, the devil preyed on someone more vulnerable to evil deeds and slowly but surely encourages them to go farther, and eventually that bully starts killing people, it's a rough analogy but yeah.
She was trash her first life time sheeesh